The general objectives of this proposal are to resolve the ontogeny, distribution, and turnover of the surface antigens on the flagellum and non-flagellated regions of several uniquely approachable unicellular systems. The ability to separate flagellar membranes from other surface membranes together with the now well documented evidence that flagellar surface antigens can be separated from those of the rest of the cell suggests that by appropriate tagging experiments specific surface domains can be followed during developmental phases such as cell division and regeneration of flagella after artificial amputation. The specific role of microtubules in surface antigen distribution and maintenance suggested from earlier work will be further defined through the direct biochemical characterization of several flagellar membrane-microtubule associations and through an analysis of the distribution of surface glycosyltransferases, and flagellar mastigonemes. Some of the unusual properties of the microtubules of these systems will also be further assessed through the use of analytical gels, and through the application of several promising herbicidal mitotic inhibitors which may selectively depolymerize microtubules in vivo in these colchicine-insensitive systems.